The present invention relates to a coating layer for a fabric for toothed belts.
A toothed belt is known that comprises a body made of elastomeric material, in which a plurality of longitudinal filiform resistant inserts, hereinafter referred to as xe2x80x9ccordsxe2x80x9d, is embedded, and comprising a plurality of teeth coated with a coating fabric.
Each component of the belt contributes to increasing belt performance in terms of mechanical resistance in order to reduce the risk of breaking of the belt and to increase the specific transmissible power.
The coating fabric of the belt increases resistance to abrasion and hence protects the working surface of the belt from wear which is due to rubbing between the sides of the teeth of the belt and the sides of the grooves of the pulley with which the belt interacts.
In addition, the coating fabric reduces the coefficient of friction on the working surface and reduces the deformability of the teeth, so preventing their failure.
The coating fabric used may consist of a single layer or, alternatively, may be double-layered so as to guarantee greater robustness and greater rigidity.
The fabric is normally treated with an adhesive, for example resorcinol-formaldehyde latex (RFL) to increase adherence between the body and the fabric itself.
Also known are numerous methods for increasing the resistance to wear of drive belts by modifying the structure of the coating fabric or by carrying out different treatments on the fabric. There are known, for example, treatments of fabrics for toothed belts in which the fabric is treated with halogenated polymers.
The above types of treatment, however, do not lead to any considerable increase in wear resistance because the coating fabric of the toothed belt, during use, in any case constitutes the working surface.
The purpose of the present invention is therefore to obtain a toothed belt with a clearly improved wear resistance, and a corresponding fabrication process which may be applied to any type of toothed belt and may be easy to implement.
According to the present invention, a toothed belt is made, comprising a body and a plurality of teeth, where the teeth are coated with a fabric, the toothed belt being characterized in that it comprises a resistant layer which provides an external coating for the fabric, and in that the resistant layer comprises a fluorinated plastomer, an elastomeric material, and a vulcanizing agent, the fluorinated plastomer being present in the resistant layer in an amount greater than that of the elastomeric material.
Also provided according to the present invention is a process for the preparation of a toothed belt, comprising the step of forming the resistant layer separately from the fabric.